Boat drive

ABSTRACT

Boat Drive System comprising as an integral unit, a propeller, propeller driving shaft with suitable bearings and seals, a duct having an inlet and outlet end oriented essentially parallel to the longitudinal axis of the boat within which said propeller rotates in a plane essentially normal to the longitudinal axis of the duct, and steering and reversing vanes within the discharge end of such duct. Said boat drive incorporates prior art ducted fan principal to improve efficiency, performance, safety, and reduce cost of boat drive systems available principally for pleasure craft.

United States Patent [191 Baggs BOAT DRIVE [76] Inventor: Joseph E. Baggs, 13632 Lanning St.,

Garden Grove, Calif. 92643 [22] Filed: Mar. 2, 1973 [211 Appl. No.: 337,753

[52] US. Cl. 115/39, 114/145 R, 115/12 R, 115/34 R, 115/35 [51] Int. Cl B63h 5/16 [58] Field of Search 115/12 R, 12 A, 34 R, 35, 115/39, 42; 114/151, 145 R, 163, 166; 239/265.29

[56] References Cited UNITED STATES PATENTS 1,344,518 6/1920 Rees 115/42 X 2,343,711 3/1944 Rusteberg 115/42 X 2,551,371 5/1951 Grigg 115/39 x 3,611,980 10/1971 Van Veldhuizen 115/12 R 1111] 3,823,684 451 July 16,1974

3,636,909 1/1972 Benson 115/34 R Primary Examiner-Lloyd L. King Assistant Examiner-Randolph A. Reese Attorney, Agent, or Firm-Max Geldin [57] ABSTRACT Boat Drive System comprising as an integral unit, a propeller, propeller driving shaft with suitable bearings and seals, a duct having an inlet and outlet end oriented essentially parallel to the longitudinal axis of the boat within which said propeller rotates in a plane essentially normal to the longitudinal axis of the duct, and steering and reversing vanes withinthe discharge end of such duct. Said boat drive incorporates prior art ducted fan principal to improve efficiency, performance, safety, and reduce cost of boat drive systems available principally for pleasure craft.

, ims, 3 DwiesEEHs PATENTEU JUL 1 61974 suamurz PATENTEUJUU 6l974 SHEET 2 OF 2 BOAT DRIVE This invention relates to boat drive systems primarily for pleasure'craft wherein the application results in an improvement over currently available drives in efficiency,performance and safety and is relatively less expensive and lighter in weight; as an example, a typical application of this invention in a water ski boat provides optimum performance at both low speed and high speed, skier protection from propeller injuries and propeller protection in shallow water when beaching. Maneuverability, braking and reversing are also improved with less weight and mechanism complication thereby minimizing cost. The boat drive systems of this invention transforms the driving engine shaft power to thrust for the purpose of propelling the boat as do other prior art boat drive systems.

Prior art boat drives may generally be identified in one of four catagories; (1) The outboard motor which incorporates an offset drive with exposed propeller and integral engine all of which is rotatable about an approximate vertical axis for steering. The outboard depends upon rotation of the entire unit about a lateral axis for obstruction clearance and beaching. The outboard is limited in power because of transom strength. The effective draft of a boat with outboard drive is increased by propeller diameter plus approximately percentwhen in the normal drive position. (2) Inboard out drives which are comprised of a through the transom offset steerable unit with exposed propeller wherein the engine is mounted in a fixed inboard position and is less restrictedin horsepower. Obstruction clearance provision and effective draft are essentially the same as the outboard. (3) The jet drive which is a unit incorporating an inboard engine driven impeller, the housing of which is completely inboard and/or does not add to the effective draft of the boat, the inlet to said impeller terminates as'a bottom mounted flange so that propulsion water flow to the impeller diverges upward from the longitudinal axis of the boat at angles in the order of 30. The exit of the jet drive converges to a steerable nozzle at approximately the static water line. (4) The inboard which consists of an exposed propeller located beneath the stern of the boat and forward of a rudder. Said propeller is driven by a shaft which passes through the bottom of the boat at a shallow angle and is supported by suitable bearings and water seals attached directly to the boat. Said shaft is driven by an inboard engine usually equipped with a clutch and forward and reverse gear transmission. No provision is made for obstruction clearance and effective draft is essentially the same as l and 2.

All of the aforementioned prior art drive systems have limitations and or disadvantages over which the boat drive system of the present invention constitutes a substantial improvement. u

According to a preferred embodiment of the invention, aboat drive system is provided comprising a duct, defining the propulsion fluid flow path having a forward facing inlet, said duct forming the other casing of said drive and designed to be oriented on and partially within a boat hull so that its longitudinalaxis is essentially parallel to the longitudinal axis of said boat, a propeller driving shaft, extendingthrough said duct wall at its uppermost point near the forward or inlet end at an angle not exceeding 10 from the longitudinal axis, said shaft being free to rotate within suitably supported bearings and sealed against water leakage at the point where the shaft passes through the duct. The aft endof said shaft terminates at a point centrally located within said duct which is cylindrical in shape at said termination point. A propeller is affixed to the aft end of said shaft and having a minimal tip to duct wall clearance and driven by said shaft, said shaft being driven by an integrally mounted V gear drive. Said V gear drive is driven by an engine suitably coupled to the driving shaft of said V" gear drive and mounted to the boat ing mode. Thus,the'duct exit area can be between 40 and 60 percent of the duct area at the plane of said propeller. i

A feature of the present invention is the utilization of prior art .technology of ducted fan systems combined with the manipulation of fluid flow by the use of semibalanced vanes thereby eliminating expense and weight of complex reversing gears, clutches and steering mechanisms. The boat drive of this invention also provides propulsion fluid flow exhaust at or below normal boat water line thereby improving boat wake which is an important consideration to water skiing.

Since the boat drive described herein incorporates a ducted-propeller, personal safety and obstruction protection is essentially equivalent to the jet drive. An advantage is optimum performance at both low speed and high speed, lack of protrusions aft of the transom, adaptability to both V bottom and flat bottom boats, minimum effective draft increase and propeller/drive shaft damage protection.

The invention will be more clearly understood by the description below of a preferred embodiment taken in I connection with the accompanying drawing wherein FIG. 1 is a side longitudinal partial cross-sectional view of the boat drive installed in a typical manner according to the invention.

FIG. 2 'is a bottom view of to the invention.

FIG. 3 is anend view of the installation as compared with conventional propeller type installation.

Referring to the drawing, FIG. 1, there is shown a boat drive 1, having a duct'2 with inlet 3 and outlet or exhaust 4 through which thepropulsion water flows. Said duct 2 is circular in cross section from the'plane the installation according of the propellerfforwardnwithin duct 2, propeller 6 is v centered at a point of maximum diameter-of duct 2. Propeller 6 is affixed to and driven by shaft 7 which is free to rotate within bearings 8 and 9. Bearing 8 is supported by strut 10, which is affixed to the upper inside 5 wall of duct 2. Bearing 9 incorporates a seal or packing gland to prevent water leakage into the boat. Bearing 9, is also affixed to and supported by the upper wall of duct 2. Gear box V drive 11 is affixed to the upper plished as a part of factory assembly with adequate tooling. It can be seen therefore, that if adequate component structual integrity is provided in manufacturing the boat drive of this invention the life expectancy and reliability of the drive train comprising 6 through 11 are greatly enhanced. As referenced, boat transom 24 and engine drive shaft are shown. Still in reference to FIG. 1, it will be noted in modified cross-section ports 12 are provided within the sidewalls of duct 2. This may be also seen in bottom .view FIG. 2. Within ports 12 are vanes 13, R & L, faired with the sidewalls of duct 2 when in the static condition. Vanes 13, R & L, operate in two modes and are used for braking, reversing and to augment steering. Vanes 13, R & L, rotate about axes 14, R & L, which are located so that moderate positive stability is evident when actuated by the boat operator for reverse and/or braking at all forward or reverse speeds straight, i.e., no turn. Referring to FIG. 2 vanes 13, R & L are shown by solid line in the full reverse mode. In the forward running mode vanes 13 R & L FIG. 1 and 2 are not controllable and are free to rotate about axes 14 R and L respectively, and are directed by the influencing fluid flow stream. Since the vanes 13, R & L, static and dynamic stability in nonairated fluid (water) is positive, the vanes will trail thereby opening ports 12, FIG. 1 8c 2, when the propulsion fluid flow path is directed by rudder 15 to turn the boat. It should be noted that with high performance boats, a high speed turn may expose vane 13R or 13L on the outboard side of the turn to airated water or air. The fluid density difference between the'water within duct 2 and airated water or air on the outside surface of they outboard vane 13, R or L, may cause instability. For this reason, in preferred practice, a vane stop is provided which is mechanicallyengaged and automatically linked to the boat controls so that in a left turn, for example, vane 13L is free to rotate about axis 14L but vane 13R is locked, and conversely the opposite for a right turn condition. Still in reference to FIG. 2, an inlet protective rail 25 is provided and is of streamlined cross-section. Large diameter drive systems may utilize additional rails which should be staggered to minimize inlet drag. Boat drive mounting flange 17 is provided. FIG. 3 represents a stern view of a typical boat drive installation of this invention. It will be noted that the effective draft of the boat 18 is considerably less than that of the same boat with prior art conventional exposed propeller shown in phanton as disk 19 and draft 20. Referring again to FIG. 1, a shallow divergence angle 23 is shown between the mean propulsion fluid flow path 21 and keel line 22. In practice this diver gence angle 23 may be varied from essentially 0 to 5 depending upon the planing attitude of the hull employed. The preferred embodiment for example, indicates a divergence of approximately l which would represent optimum positioning for a relatively level planing boat hull. It is pointed out that the shallow divergence angle discussed above represents a considerable advantage over prior art ducted systems particularly at high speed in that duct flow turbulence, fluid flow separation and propeller and/or impeller cavitation are minimized.

While I have described particular embodiments of my invention for the purpose of illustration, it should be understood that various modifications and adaptations thereof may be made within the spirit of the invention as set forth in the appended claims.

What is claimed is:

1. A boat drive comprising means forming a duct, said duct defining the propulsion fluid flow path and having a forward facing inlet, said duct adapted to be oriented on and partially disposed within a boat hull, with the longitudinal axis of said duct essentially parallel to the longitudinal axis of said boat hull, a propeller drive shaft, said shaft extending through the wall of said duct at the top thereof and adjacent-the forward inlet thereof, said shaft being disposed at an angle not exceeding 10 from the longitudinal axis of said duct, supporting bearings mounted on said duct means, said shaft being supported for rotation within said bearings, said shaft being sealed at its .point of passage through said duct wall, the aft end of said shaft terminating at a point within said duct centrally located adjacent the aft end of said duct, said duct being cylindrical in shape at said shaft termination point and said duct converging aft of said shaft termination point to form a duct exit, a propeller mounted at the aft end of said shaft and having a small tip to duct wall clearance, and driven by said shaft, means for driving said shaft, controlling and reversing vanes'mounted for rotation on a vertical axis in the wall of said duct exit, and a'rudder mounted on a vertical axis on said duct exit wall, the axis of rotation of said rudder being positioned aft of said propeller and forward of the axis of rotation of said vanes.

2. A boat drive as defined in claim 1, wherein propulsion fluid flow pathforward of said propeller as defined by said duct diverges at an angle from 0 to 5 from boat keel line when installed.

3. A boat drive as'defined in claim 1, having said duct exit area between 40 and 60 percent of said duct area at the plane of said propeller.

4. A boat drive as defined in claim 1 said controlling vanes operating in two modes to brake and reverse boat on which said boat drive is installed and to augment steering of said'boat.

5. A boat drive as defined in claim 1, said inlet of said duct being guarded with rail or rails.

6. A boat drive as defined in claim 1, said boat drive adding less than propeller diameter to the effective draft of boat on which drive is installed.

7. A boat drive as defined in claim 1, comprising a pair of said controlling and reversing vanes, each mounted in opposite wall portions of said duct exit, and free to rotate in the forward running mode, and faired within said duct exit wall portions in the straight forward operating mode.

8. A boat drive as defined in claim 1, said supporting bearings comprising a pair of bearings, one of said bearings being disposed at the top of said duct wall and at said point of passage of said shaft through said duct wall, a seal in said last mentioned bearing for sealing said shaft, a second bearing for said shaft being mounted within said duct wall adjacent said propeller.

, 9. A boat drive as defined in claim 1, said shaft driving means being a V gear drive, said V gear drive being mounted on said duct means exteriorly thereof. 

1. A boat drive comprising means forming a duct, said duct defining the propulsion fluid flow path and having a forward facing inlet, said duct adapted to be oriented on and partially disposed within a boat hull, with the longitudinal axis of said duct essentially parallel to the longitudinal axis of said boat hull, a propeller drive shaft, said shaft extending through the wall of said duct at the top thereof and adjacent the forward inlet thereof, said shaft being disposed at an angle not exceeding 10* from the longitudinal axis of said duct, supporting bearings mounted on said duct means, said shaft being supported for rotation within said bearings, said shaft being sealed at its point of passage through said duct wall, the aft end of said shaft terminating at a point within said duct centrally located adjacent the aft end of said duct, said duct being cylindrical in shape at said shaft termination point and said duct converging aft of said shaft termination point to form a duct exit, a propeller mounted at the aft end of said shaft and having a small tip to duct wall clearance, and driven by said shaft, means for driving said shaft, controlling and reversing vanes mounted for rotation on a vertical axis in the wall of said duct exit, and a rudder mounted on a vertical axis on said duct exit wall, the axis of rotation of said rudder being positioned aft of said propeller and forward of the axis of rotation of said vanes.
 2. A boat drive as defined in claim 1, wherein propulsion fluid flow path forward of said propeller as defined by said duct diverges at an angle from 0* to 5* from boat keel line when installed.
 3. A boat drive as defined in claim 1, having said duct exit area between 40 and 60 percent of said duct area at the plane of said propeller.
 4. A boat drive as defined in claim 1 said controlling vanes operating in two modes to brake and reverse boat on which said boat drive is installed and to augment steering of said boat.
 5. A boat drive as defined in claim 1, said inlet of said duct being guarded with rail or rails.
 6. A boat drive as defined in claim 1, said boat drive adding less than propeller diameter to the effective draft of boat on which drive is installed.
 7. A boat drive as defined in claim 1, comprising a pair of said controlling and reversing vanes, each mounted in opposite wall portions of said duct exit, and free to rotate in the forward running mode, and faired within said duct exit wall portions in the straight forward operating mode.
 8. A boat drive as defined in claim 1, said supporting bearings comprising a pair of bearings, one of said bearings being disposed at the top of said duct wall and at said point of passage of said shaft through said duct wall, a seal in said last mentioned bearing for sealing said shaft, a second bearing for said shaft being mounted within said duct wall adjacent said propeller.
 9. A boat drive as defined in claim 1, said shaft driving means being a ''''V'''' gear drive, said ''''V'''' gear drive being mounted on said duct means exteriorly thereof. 